Parallel reactors are widely used in research into chemical reactions, in particular for high throughput experimentation. In high throughput experimentation, a plurality of relatively small scale reactors is placed in parallel. In each reactor, a different experiment takes place. Usually, conditions and/or reactants are varied slightly over the different reactors. For example all reactors are operated at the same pressure and temperature, but all contain a different reactant. After the experiments are carried out, the results of the experiments are compared with each other, and for example interesting reactants (e.g. catalysts) are identified. Carrying the experiments out in parallel leads to a significant reduction in the time it takes to come up with experimentation results.
Usually, in high throughput experimentation, the reactors are small, as are the amounts of reactants that are used. Often, flow through reactors are used, and the flow rates of the fluid flows are also low. Typical reactor sizes do not exceed 1 cm in diameter, and when for example catalytic activity is tested, typically a few grams of a potential catalyst are present in each reactor. Sometimes even less potential catalyst is used, e.g. between 0.005 and 1 gram. Flow rates are usually less than 10 ml/hour for liquids and/or less than 150 Nml/minute for gas. The typical low flow rate used in high throughput reactions makes controlling the fluid flow through the individual reactors hard.
In order to be able to compare the results of the experiments that are carried out in the different reactors with each other, it is important to accurately control the process conditions of each experiment. Such process conditions include e.g. temperature, pressure and flow rate.
A different use of parallel reactors in chemistry is production of chemical compounds using microreactors. Microreactors are of similar size or slightly larger than the reactors used in high throughput experimentation. When it has been proven that a certain compound can be produced at a small scale, using a small scale reactor, a plurality of such small scale reactors is arranged in parallel. The compound is then produced in these reactors, using the same reaction conditions as in the original, single reactor.
So, also in this application of parallel reactors, it is important that the same reaction conditions are present in all reactors.
EP1888224 describes a system for high throughput experiments. In this known system, multiple parallel flow-through reactors are present. In each flow-through reactor a fixed bed is present that contains a potential catalyst. All reactors receive a reaction fluid from a fluid source. The fluid flow from the fluid source is split up into multiple fluid flows, each going to a reactor. In the reactors, a reaction may take place. The reactor effluent is then analyzed, for example in order to determine whether the potential catalyst is a good candidate for further investigation.
In the system of EP1888224, the pressure in the reactors is controlled by a back pressure regulator. This back pressure regulator comprises a plurality of flow channels. Each flow channel receives the flow of reactor effluent from its own dedicated reactor. The flow channels extend through a common pressure control chamber, in which a control gas at a reference pressure is present. The flow channels have flexible walls, so that the pressure in the common control chamber can influence the cross sectional area of the flow channels, and therewith control the pressure in the reactors upstream of the flow channels. The reference pressure in the pressure control chamber is controlled by a single pressure controller. In the system of EP1888224, the pressure is controlled in such a way that the backpressure of all reactors is the same. This is however not always desired. The backpressure regulator of EP1888224 can be modified in such a way that the common pressure control chamber is divided up into several compartments in which the reference pressure can be controlled individually. So, different compartments can have different reference pressures. Alternatively, individual dome regulators could be used downstream of each reactor.
However, such a setup would require a plurality of pressure controllers, each pressure controller being dedicated to one compartment of the pressure control chamber. This is disadvantageous, as pressure controllers are generally bulky and expensive equipment.